Conventionally, in the product exhibition in the show window or in the stage production in event facilities, there has been used illumination presentation to attract the attention of customers and audience and strengthen the impression of exhibits and the like by projecting light from an illumination apparatus such as a spotlight onto a projection target object. As the illumination presentation, in addition to varying the light intensity and the projection position, a cocktail beam obtained by combining primary lights such as red, green and blue lights may be projected.
Also, there is known a light projection apparatus which detects a shadow area of an object, corrects the shadow area such that a projection area of a light projection unit matches the shadow area on the back of the object, sets the corrected shadow area as a light projection range, and projects a projection light in a range in which the object is present (see, e.g., Japanese Patent Application Publication No. 2012-243665 (JP2012-243665A)).
However, when each light is irradiated to a specific location by using a plurality of spotlights (e.g., R, G, B and the like) with different emission colors, as shown in FIG. 22A, a light overlapping portion becomes white whenever lights overlap each other, and a presentation effect using the light colors is rather poor. In other words, light cannot be “overwritten” as shown in FIG. 22B.
For example, by using a plurality of spotlights, as shown in FIG. 23A, it is assumed that each of a circular light 10a and an annular light 10b with different light colors is irradiated to a specific location. In this case, at a light overlapping portion, the lights are mixed as shown by an area 10c in FIG. 23B. Therefore, as shown in FIG. 23C, it is difficult to specify a front-back relationship between the lights, i.e., to specify that the light 10a is in front of the light 10b as shown in FIG. 23C, or when the light 10b is in front of the light 10a as shown in FIG. 23D and, thus, it is difficult to enhance the presentation effect by emphasizing the specific light. Further, since a general spotlight irradiates a circular light, which illuminates not only the projection target object, but also the background, attention of customers and the like to the projection target object may be insufficient.
Also, in the light projection apparatus described in JP2012-243665A, it is possible to project a plurality of spot lights by dividing the projection range, but there is no concept of the front-back relationship to determine which light is in front of or behind the other when the spot lights are overlapped. Therefore, similarly to the spotlight, there is a limit to the presentation effect when the lights are overlapped in the projection range.